Data commit

Task/Dutch-national-flag-problem/SQL/dutch-national-flag-problem.sql

@@ -0,0 +1,35 @@
+-- Create and populate tables
+create table colours (id integer primary key, name varchar(5));
+insert into colours (id, name) values ( 1, 'red'  );
+insert into colours (id, name) values ( 2, 'white');
+insert into colours (id, name) values ( 3, 'blue' );
+
+create table balls ( colour integer references colours );
+insert into balls ( colour ) values ( 2 );
+insert into balls ( colour ) values ( 2 );
+insert into balls ( colour ) values ( 3 );
+insert into balls ( colour ) values ( 2 );
+insert into balls ( colour ) values ( 1 );
+insert into balls ( colour ) values ( 3 );
+insert into balls ( colour ) values ( 3 );
+insert into balls ( colour ) values ( 2 );
+
+-- Show the balls are unsorted
+select
+	colours.name
+from
+	balls
+	join colours on balls.colour = colours.id;
+
+-- Show the balls in dutch flag order
+select
+	colours.name
+from
+	balls
+	join colours on balls.colour = colours.id
+order by
+	colours.id;
+
+-- Tidy up
+drop table balls;
+drop table colours;